Configuraciones de cámara HD para ganar latitud ENG

Configuraciones de cámara HD para ganar latitud
Technical information
HDCAM 1:1.85 25fps Shutter 1/50 Sony F-900 Camera Canon EJ series lenses
adapted to HD Shooting with Arrilaser Intermediate 5242/ Kodak Premier Positive
In Shooting Audiovisual's 6th issue, Marta Rey published an article about different
aspects of production. In this text she offers all the technical information regarding
the choice of Betacam SP format for certain sequences in a film, given its suitability to
co-exist with footage shot in HDCAM. The other objective was to achieve as much
latitude as possible with the Sony F-900 to obtain greater detail in both the highlights
and low lights.
“El regalo de Silvia” tells four stories sharing the same starting point: Silvia's videodiary, therapeutic sessions whose emotional tone link us to the other narrative
strands. Silvia decides to donate her eyes, her liver and her heart, which are received
by people from very different backgrounds. The heart goes to a middle-low class man
with ambitions; the liver to a hoodlum who wants out of his criminal career, and her
eyes are received by a wealthy young woman who lost her parents in a car accident.
The three stories of the receptors were shot in HD given its proven quality and
convenience when doing multiple takes. For Silvia's video-diary we wanted to use a
format that, while being of an inferior quality and having the look of domestic video,
would not alienate the audience when shown alongside the HD footage. We tried with
two different formats: DVCAM and Betacam SP.
For Silvia's video-diary we wanted to use a format that, while being of an inferior
quality and having the look of domestic video, would not alienate the audience when
shown alongside the HD footage. We chose Betacam SP because it was very important
to achieve a format with enough detail to capture the actress? expression while still
looking like a home video
Once we had colour graded, linked the fields in postproduction and filmed to 35mm
we decided for the analogue format whose definition was worst than DVCAM, with
smoother transitions between the colours and the edges. As we can see in Fig. 1, the
image was very different to the one in HD, while still retaining enough detail of the
skin. It was very important to achieve a format with enough detail to capture the
actress? (Barbara Goenaga ) expression while still looking like a home video. We
decided not to shoot with an actual domestic video camera in miniDV due to its poor
definition, as well as its poor reproduction of colour, which, when compared to the HD,
would have destroyed the reality of the film.
Once we had decided on the Sp format for the video-diary we focused all our energy
in achieve the largest latitude as possible with the Sony F-900 to obtain as much
detail as possible both in the high and the low lights. We photographed a Kodak grey
card with the camera's standard setup, and then we did the same using the
modifications made by Ben Allan (www.cinematography.net), which increase the
latitude by modifying the Knee, Whipe Chip, Slope, gamma, etc. controls.
These changes not only increase the latitude in high lights, they also make the loss of
detail less dramatic than with the standard. On this set-up we modified the gamma
and the black gamma by using the ITU-709 colour matrix. In the gamma menu we
used coarse 0.45 and the 5th table, which reduces the compression of blacks and
obtains the curve shown in the graph.
Comparing it to the standard we appreciate the increase in detail in the blacks and the
change in the high lights, making the shoulder of the curve closer to the negative. The
latitude increases around 2 F-stops in relation to the standard. It goes without saying
that with this configuration colour grading becomes essential, because the image
captured by the camera has little contrast, appearing slightly washed out, while
having great amount of detail ( see stills ).
According to Jordi San Agustín, colour grading operator at Image Film digital: ?For the
digital colour grading, the camera tests allowed us to find the largest latitude in
response to the high and lowlights, so we always have accurate values for the whole
of the density curve, which allows us to find the right balance for densities as well as
for colour space and obtain a great transfer to 35mm?.
To conclude, in Table 1 we can observe the relation of all the values involved in the HD
process. With the set-up we used the camera's sensitivity is around 400ASA, however
we chose to use 500 ASA by underexposing slightly to achieve an even better
response in the highlights, given the good behaviour of the camera with shadows.